A thin layer of frost coats the outside of the thick, cold glass. A generous chunk of chocolate cake sits atop the shake's brown surface, stuck in the middle like some wayward jungle explorer suspended in quicksand. A circular swoop of chocolate sauce drapes across it all.

I hesitate for a second, reaching for a spoon but eyeing a straw. The spoon quickly makes me feel foolish, as I slurp awkwardly from it. I ditch it and grab the straw, a sometimes-questionable milkshake method. If they're too dense to sip, you get a furrowed brow and a headache. If they're too soupy, it's done in a flash.

But this is a bourbon-and-cake shake at Chuck's, Ashley Christensen's fashionable burger outpost in downtown Raleigh. It's so smooth I manage it easily without flatware. The spoon only proves useful when I reach the bottom, since I need something more substantial for scooping up leftover bits of crumbly cake. Slightly buzzed and completely sated in the late afternoon, I oblige, digging in until I'm done.

It seems hard to screw up something as simple as a milkshake—it's just milk and ice cream, right?—but Chuck's elevates the options with the tantalizing addition of alcohol. Most milkshakes include a splash of milk to make the blend creamier, but the liquor serves the same purpose here; otherwise, a manager tells me, you'd end up with an alcohol-infused dairy soup. The ice cream is so cold when it hits the kitchen's Hamilton Beach blender that it needs some extra juice to boost it to a temperature that allows for the correct smoothness. That texture, as I learned firsthand, makes it easier to enjoy with a straw than a spoon. And these spiked shakes are boozy wonders that make you glad to be a grown-up.

Chuck's uses Howling Cow ice cream, the famed product of N.C. State's Department of Food Science, for the foundation. The year-round, non-alcoholic additions include updates on the basics—dark chocolate cake, salty peanut butter and roasted banana, and Madagascar malted vanilla, each topped with some whimsical delight, like the cake. Specials shift every few weeks, from a current offering that incorporates cold brew coffee from Christensen's nearby Joule, to fresh fruit throughout the spring and summer. Sometimes the specials are cereal-based (Captain Crunch or peanut butter cocoa puff) or even pastry-inspired, such as Chuck's more recent carrot cake shake.

Photo by Ben McKeown

Still, even as the specials come and go, the manager assures me, the standard options outsell them all. I follow that lead, and the classic chocolate calls me—and so does the bourbon.

The staff at Chuck's has recommended alcohol pairings for all the shakes, including Old Grand-Dad bourbon, Sailor Jerry's spiced rum, Cruzan dark rum, Bailey's Irish Cream, or Kahlúa. Still, if you find yourself craving a Madagascar malted with tequila, they'll indulge you. I'm not feeling quite that adventurous, but I love bourbon and chocolate in equal measure, so my decision is easy and obvious. (Kahlúa and frozen cold brew coffee was a tempting mix, too, but how many shakes and shots does someone need before four p.m.?)

You can opt for a one-ounce pour of booze or a double, which proves to be the correct choice. There's enough bourbon in the shake to taste but not so much that it smothers the sweetness of the Howling Cow. The bigger dram adds a tiny little sting behind the sweet, and, on an empty stomach, even provides a little buzz. (Oops.) Any less, though, and it might be difficult to tell much of a difference from a non-alcoholic shake.

Especially considering the slim list of ingredients, Chuck's decadent shakes aren't exactly cheap. The alcohol-free version will set you back only five dollars, but a shake with one ounce of liquor is nine dollars, while two ounces punch it all the way up to twelve. But the tall portion is generous and rich enough to share, a strategy that, as I finish my chocolate-and-bourbon dream, actually starts to make sense. If I'd only had half this one, that Kahlúa-and-coffee confection might still be an option, too.